Re: [RFC PATCH] drm/radeon: UVD GTT corruption and RV6xx coverage

[Alex Deucher]

Applied.  Thanks!

On Thu, Oct 29, 2026 at 4:05 AM Ted Bullock <tbullock@xxxxxxxxxxx> wrote:
>
> I investigated video corruption on my older iMac7,1 (RV610/M74,
> device ID 1002:94c8).
>
> When the decoder was reading compressed video from system memory while
> the GPU was drawing, it would corrupt video frames. Moving the input
> to VRAM allowed frames to decode correctly. Disabling graphics draws
> also stopped the corruption.
>
> Here is a proposal to keep UVD buffers in VRAM for this family of
> devices, as the driver already does for some other chips. The patch
> covers RV610, RV620, RV630, RV635 and RV670. These chips share the
> RV6xx decoder path and legacy R600 firmware, so I think they are
> likely to have the same hardware requirements. Someone with the
> other hardware would need to verify that.
>
> I tested this on Debian.
>
> I used Codex to help with the investigation, testing and patch.
>
> Signed-off-by: Ted Bullock <tbullock@xxxxxxxxxxx>
> ---
>  drivers/gpu/drm/radeon/radeon_cs.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_cs.c
> b/drivers/gpu/drm/radeon/radeon_cs.c
> index 2db819a..9bfd3ea 100644
> --- a/drivers/gpu/drm/radeon/radeon_cs.c
> +++ b/drivers/gpu/drm/radeon/radeon_cs.c
> @@ -125,11 +125,16 @@ static int radeon_cs_parser_relocs(struct
> radeon_cs_parser *p)
>
>                 /* The first reloc of an UVD job is the msg and that must be in
>                  * VRAM, the second reloc is the DPB and for WMV that must be in
> -                * VRAM as well. Also put everything into VRAM on AGP cards and older
> -                * IGP chips to avoid image corruptions
> +                * VRAM as well. Also put everything into VRAM on RV6xx, AGP cards
> +                * and older IGP chips to avoid image corruptions
>                  */
>                 if (p->ring == R600_RING_TYPE_UVD_INDEX &&
>                     (i <= 0 || pci_find_capability(p->rdev->pdev, PCI_CAP_ID_AGP) ||
> +                    p->rdev->family == CHIP_RV610 ||
> +                    p->rdev->family == CHIP_RV620 ||
> +                    p->rdev->family == CHIP_RV630 ||
> +                    p->rdev->family == CHIP_RV635 ||
> +                    p->rdev->family == CHIP_RV670 ||
>                      p->rdev->family == CHIP_RS780 ||
>                      p->rdev->family == CHIP_RS880)) {